IBM transistor replacements

Jon Elson elson at
Fri Nov 26 19:11:24 CST 2021

On 11/26/21 3:52 PM, Al via cctalk wrote:
> Dear all,
> A while ago I received an IBM 3286 printer, annoyingly 
> some of the transistors in the printer section have been 
> corroded. What I am having trouble with is reading the 
> part codes and finding a modern equivalent of them.
> There are two types.
> One has a Ti logo and two sets of numbers (attached). Does 
> anybody know which numbers are the part numbers and if 
> they are IBM house numbered?
> Photos of the Ti transistors and card assembly: 
> The other is an IBM transistor with what appears to be a 3 
> digit part code; for which I have been pointed to a list 
> of house numbering and equivalents on the 1401 website. I 
> was told the list is much older and I fear it might be out 
> of date. However there is an entry for the part codes on 
> my IBM transistors.
> Should I trust the list for replacements?

The cards appear to be SLT-style fabrication, it seems there 
may even be SLT modules on one of them (the 1/2" square 
aluminum-capped blocks.)

The 1401 list would be for SMS cards, they were yellow 
paper-phenolic cards with TO-5 and TO-18 discrete Germanium 
transistors.  The SLT vintage were generally all Silicon 

Almost all this stuff had IBM house numbers.


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